Small pieces of wood, such as wood chips or wood particles formed by chopping or cutting scrap lumber or trees, are frequently used as a ground cover or mulch in gardens or groomed outdoor areas. The application of a relatively thick coating of wood chips or particles which are generically referred to as "wood chips," upon the surface of the ground tend to retain the moisture within the ground, limits the growth of unwanted plants, such as weeds, and provides clear surfaces upon walking paths, in addition to providing a decorative effect in pre-selected areas.
However, wood chips generally have a dull or unattractive color. For example, they commonly become a grayish color which is visually unattractive. Moreover, unprotected wood chips generally tend to rot quickly, particularly in moist areas so that frequent additions of wood chips in such areas are required. Consequently, it is common to treat wood chips, which are to be used as ground cover or mulch, with a colorant or paint which imparts a more attractive color to a bed of wood chips and which resists rotting of the wood chips.
A known way of coloring or painting wood chips is by applying a liquid colorant upon wood chips conveyed within an auger-screw type of conveyor. Such type conveyors, which generally comprise an elongated screw contained within a trough-like housing, have been commonly used in industry and on farms for moving particulate materials along horizontal or upwardly angled paths. The paint or colorant is applied by immersing the wood chips in a pool of liquid colorant or paint at the entry end of an auger screw conveyor or by spraying the colorant upon the chips as they move along the conveyor. The immersion technique substantially saturates the chips with paint. Similarly, the spray technique tends to saturate the chips to a substantial depth. In either technique, excess paint clinging to the chips runs downwardly along the housing that surrounds the screw back into the pool of colorant or to some other drain for collection and possible re-use. When the colorant is applied at the entry of the conveyor the paint is dried to a considerable extent as the chips ave moved along the conveyor until their discharge from the conveyor. Typically the chips fall by gravity downwardly into a pile in which the chips continue drying. In the case of spray application of a colorant, the wet paint may be dried after discharge from the auger conveyor.
In painting or coloring wood chips, a considerable amount of the liquid colorant or paint is absorbed by the chips so that the chips tend to be saturated with colorant or paint. Consequently, a considerably greater amount of paint or colorant is normally used than is really necessary for the purposes of coloring the visually exposed surfaces of the chips or for preserving the chips. Since suitable colorants or paints are relatively expensive, the expense of preparing colored wood chips is considerable. This reduces the desirability of using colored wood chips for mulch purposes.
Thus, it is an object of the present invention to provide a method and apparatus which applies paint to the surfaces of wood chips, that is, small pieces of wood formed by chipping, chopping, cutting, grinding or the like, without thoroughly soaking and without saturating the chips so as to substantially reduce the amount of colorant or paint required and, consequently, to reduce the expense of such colored chips.